He's in Alabama. He's likely talking about mowing Bermuda low, which is a quasi-customary thing in the South. Your Bluegrass grows very differently and it'd kill it to mow it that low.

My advice would be to go ahead and mow it down to maybe 1.5" to get rid of the dead stems from last season's growth. But if you aerate Bermuda before it's growing rapidly you will find that weeds will tend to fill the gaps instead of grass, especially when combined with a now-short lawn that won't shade out weed seeds as well as when longer. Aerate warm season turf in the warm months. Makes a great rainy day alternative. Some boots and a poncho and you'll be fine even in the rain.